FORTRAN programs to process Magsat data for lithospheric, external field, and residual core components

The FORTRAN programs supplied in this document provide a complete processing package for statistically extracting residual core, external field and lithospheric components in Magsat observations. To process the individual passes: (1) orbits are separated into dawn and dusk local times and by altitude, (2) passes are selected based on the variance of the magnetic field observations after a least-squares fit of the core field is removed from each pass over the study area, and (3) spatially adjacent passes are processed with a Fourier correlation coefficient filter to separate coherent and non-coherent features between neighboring tracks. In the second state of map processing: (1) data from the passes are normalized to a common altitude and gridded into dawn and dusk maps with least squares collocation, (2) dawn and dusk maps are correlated with a Fourier correlation efficient filter to separate coherent and non-coherent features; the coherent features are averaged to produce a total field grid, (3) total field grids from all altitudes are continued to a common altitude, correlation filtered for coherent anomaly features, and subsequently averaged to produce the final total field grid for the study region, and (4) the total field map is differentially reduced to the pole

Flood Inundation Mapping in the Logone Floodplain from Multi Temporal Landsat ETM+Imagery

Yearly flooding in the Logone floodplain makes an impact on agricultural, pastoral, and fishery systems in the Lake Chad Basin. Since the flooding extent and depth are highly variable, flood inundation mapping helps us make better use of water resources and prevent flood hazards in the Logone floodplain. The flood maps are generated from 33 multi temporal Landsat Enhanced Thematic Mapper Plus (ETM+) during three years 2006 to 2008. Flooded area is classified using a short-wave infrared band whereas open water is classified by Iterative Self-organizing Data Analysis (ISODATA) clustering. The maximum flooding extent in the study area increases up to approximately 5.8K km2 in late October 2008. The study also provides strong correlation of the flooding extents with water height variations in both the floodplain and the river based on a second polynomial regression model. The water heights are from ENIVSAT altimetry in the floodplain and gauge measurements in the river. Coefficients of determination between flooding extents and water height variations are greater than 0.91 with 4 to 36 days in phase lag. Floodwater drains back to the river and to the northeast during the recession period in December and January. The study supports understanding of the Logone floodplain dynamics in detail of spatial pattern and size of the flooding extent and assists the flood monitoring and prediction systems in the catchment

Valproate, thalidomide and ethyl alcohol alter the migration of HTR-8/SVneo cells

BACKGROUND: Valproate, thalidomide and alcohol (ethanol) exposure during the first trimester of pregnancy is known to cause several developmental disorders. All these teratogens are known to pass the placental barrier and interfere directly with the normal development of the fetus. However, these teratogens also alter the formation and function of the placenta itself which may in turn affect the proper nourishment and development of the fetus. Optimum development of the placenta requires adequate invasion of trophoblast into the maternal uterine tissues. Changes in the migratory behavior of trophoblast by maternal exposure to these teratogens during placentogenesis may therefore alter the structure and function of the placenta. METHODS: In the present study, the effects of sodium valproate, thalidomide and alcohol on the migration of human first trimester trophoblast cell line (HTR-8/SVneo) were examined in vitro. Cells were cultured in the wells of 48-well culture plates as mono or multilayers. Circular patches of cells were removed from the center of the wells by suction, and the migration of cells into the wound was studied using microscopy. Effects of low and high concentrations of valproate, thalidomide and alcohol were examined on the healing of wounds and on the migration rate of cells by determining the wound areas at 0, 3, 6, 12, 24 and 48 h. Effects of drugs and alcohol on the proliferation and the expression levels of integrin subunits beta1 and alpha5 in cells were examined. RESULTS: The migration rates of trophoblast differed between wounds created in mono and multilayers of cells. Exposure to teratogens altered the migration of trophoblast into mono and multilayer wounds. The effects of valproate, thalidomide and alcohol on the proliferation of cells during the rapid migratory phase were mild. Drug exposure caused significant changes in the expression levels of beta1 and alpha5 integrin subunits. CONCLUSION: Results suggest that exposure to valproate, thalidomide or alcohol during the first trimester of pregnancy may change the ultrastructure of the placenta by altering the migration of trophoblast cells and this effect may be mediated by drug- or alcohol-induced changes in the expression levels of beta1 and alpha5 integrin subunits

A high temporal resolution data set of ERS scatterometer radar backscatter for research in Arctic and sub-Arctic regions

Radar backscatter in Arctic and sub-Arctic regions is temporally dynamic and reflects changes in sea ice, glacier facies, soil thaw state, vegetation cover, and moisture content. Wind scatterometers on the ERS-1 and ERS-2 satellites have amassed a global archive of C-band radar backscatter data since 1991. This paper derives three high temporal resolution data products from this archive that are designed to facilitate scatterometer research in high-latitude environments. Radar backscatter data have a grid spacing of 25 km and are mapped northwards from 60°N latitude over intervals of one, three, and seven days for the period 1991-2000. Data are corrected to a normalized incident angle of 40°. Animations and full-resolution data products are freely available for scientific use at http://merced.gis.ucla.edu/scatterometer/index.htm

Melting of small Arctic ice caps observed from ERS scatterometer time series

Time series of active microwave backscatter data from the ERS Wind Scatterometers are used to demonstrate (1) the timing of melt onset can be observed over small ice caps, as well as the major ice sheets and multi-year sea ice; add (2) temporally integrated backscatter reduction (R) is strongly correlated with total annual positive-degree-days (PDD), as measured at four automated weather stations on the surface of the Greenland Ice Sheet. The latter is particularly interesting because unlike melt onset, R is a measure of melt processes integrated over an entire ablation season. Both methods work owing to the well-known sharp decrease in radar backscatter triggered by the appearance of liquid water in a glacier snowpack. Melt onset and R are determined for 14 small Arctic ice caps from 1992-2000. Interannual and regional variability in the timing of melt onset are comparable, averaging 33 ± 9 and 38 ± 13 days, respectively. Regional variability in R exceeds interannual variability, averaging 906 ± 164 and 309 ± 130 dB·d, respectively. The brevity of the derived nine-year records limits their statistical testing for trend. However, their qualitative interpretation suggests that the timing of melt onset is more variable for Arctic ice caps than for sea ice, and the intensity of summer surface melting increased by about 20% in the 1990s. © 2003 by the American Geophysical Union

Seasonal fluctuations in the mass of the Amazon River system and Earth’s elastic response

[1] A GPS station in Manaus, near the center of the Amazon basin, manifests an annual cycle of vertical displacement with a peak-to-peak amplitude of 50-75 mm. This is by far the largest crustal oscillation observed to date, and nearly 2 -3 times larger than the amplitude predicted for this region. Vertical ground displacement is strongly anticorrelated with the local stage height of the Amazon river, with no detectable time lag between the two time series. This suggests that we are observing, for the first time, a purely elastic response to changes in the weight of a flowing river system. We use a simple hydrological model to relate stage height to the regional pattern of flooding, and argue that the elastic oscillations observed in Manaus are dominated by changes in water loading developed within $200 km of the GPS station. Citation